The United States is pressing for enforcement action against Iran after a United Nations report on December 15 found Tehran violated UN sanctions against testing nuclear-capable missiles.

U.S. Ambassador to the UN Samantha Power, who along with representatives from Britain, France, and Germany asked for the report on Iran's October 10 missile test, said the United States will press for enforcement.

"This council cannot allow Iran to feel that it can violate our resolutions with impunity," she told a UN Security Council meeting considering the report from its Iran sanctions committee on December 15.

Power accused members of the council who she did not identify of refusing to take action against Iran despite evidence of several sanctions violations since Tehran signed a landmark deal to curb its nuclear weapons development in July.

"Instead of an effective, timely response, the Security Council has dithered," she said, stressing the importance of sanctions enforcement for "a credible, enforceable nuclear deal."

In addition to the October missile launch, Power said that nothing has been done in response to apparent violations by Iran in allowing a visit to Moscow by Quds Force commander Qasem Soleimani, who is under a UN travel ban, and sending a banned shipment of arms that was intercepted off the coast of Oman in September.

Beyond those alleged violations, the United States is investigating reports that Iran fired a second nuclear-capable missile in a test last month in violation of UN sanctions. The White House has said it may raise that test as well before the UN.

Tehran insists that its missiles are not designed to carry nuclear weapons and therefore don't violate UN sanctions.

But the UN sanctions committee found that the missile launched in October was capable of delivering nuclear weapons. The report said the missile had a range of at least 1,000 kilometers and a payload of at least 1,000 kilograms.

The panel said a much smaller missile -- one with a range of only 300 kilometers and a payload of 500 kilograms -- would be large enough to deliver weapons of mass destruction.

White House Spokesman Josh Earnest said earlier that President Barack Obama would support new sanctions in response to the October test, but only if intelligence officials concluded they would benefit U.S. national security.

The October launch was Iran's first test of a ballistic surface-to-surface missile since the nuclear deal was signed. In referring the matter to the UN, the United States and its allies called for taking "appropriate action" against Tehran.

Diplomats said it was possible for the UN sanctions committee to blacklist additional Iranian individuals or entities, something Washington and its European allies are likely to demand.

British UN Ambassador Matthew Rycroft told reporters December 15 that it is "absolutely crucial that the Security Council upholds its responsibilities and does respond effectively to what appears to have been a breach."

But Russia and China, which dislike the sanctions on Iran's missile program, might block any such moves, diplomats said.

Republicans in the U.S. Congress who disapproved of the Iran nuclear deal seized on the UN findings December 15 as grounds for additional congressional sanctions. Even some Democrats supported unilateral U.S. action on the missile violations.

Democratic U.S. Senator Chris Coons told Reuters it was up to the UN Security Council to act. But if it does not, the United States should take action, including imposing unilateral sanctions on Iranians responsible for the missile tests, he said.